Spot prevention in light-sensitive silver halide emulsion layers



United States Patent SPOT PREVENTION IN LIGHT-SENSITIVE SILVER This invention relates to improved photographic materials comprising a light-sensitive silver halide emulsion layer which material has added thereto special compounds capable of reducing or inhibiting the formation of spots in the silver halide emulsion layer.

The manufacture and processing of photographic material should be elfected with complete exclusion of dust; Consequently, provision is made in the art to free the drying air from dust particles by filtration.

Despite precautionary measures, however, it is not possible completely to prevent dust particles being deposited, more especially during the manufacture of the photographic material, and these particles become visible as dark or light spots on the processed photographic material, depending upon whether their action is sensitizing or desensitizing.

Partciularly fine metal particles, for example, of iron, aluminium, chromium, nickel or copper, their salts or such compounds as oxides, are very disturbing in this respect. Various types of additives have been proposed in the literature to prevent such disturbances. For example, British Patent 623,448 describes aldoximes, which are added to the developer solution or the emulsion in order to take up copper ions. Further publications recommend the use of acyloins, alkali metal pyrophosphates, metaphosphates, tripolyphosphates and hexametaphosphates, alkali metal oxalates, tartrates, silicates, carbonates and bicarbonates, tungstates, rhen'ates, osmates, molybdates, chromates and derivatives of ethylene diamine tetracetic acid for restricting the spot formation due to dust particles.

It has, however, been found in practice that either the efieet of these compounds is limited to certain emulsions, or that disadvantageous side efiects occur, such as deterioration of the latent image, fogging of the emulsions during storage, deterioration in the mechanical properties of the photographic material or greater susceptibility to scratching.

It has now been found that the formation of spots in photographic materials comprising a support and a lightsensitive silver halide emulsion can be substantially avoided by incorporating into said material phenolic compounds which are substituted in ortho-position to the phenolic hydroxyl group by an azomethinyl or an aminomethyl group the nitrogen atoms of which are substituted by a radical carrying acarboxylic acid or a sulfonic acid group. Such compounds may be illustrated by the following formulae:

3,310,405 Patented Mar. 21, 1967 wherein R and R each represent a member selected from the group consisting of a hydrogen atom, a halogen atom such as chlorine, bromine, iodine, an alkyl group having 1 to 5 carbon atoms, an alkoxy group having 1 to 5 carbon atoms in the alkyl radical, a hydroxy group or any other substituent which is inert with regard to the silver halide emulsion, such as sulphonic acid or carboxylic acid radicals, esterified carboxylic acid groups and hydroxy alkyl groups;

X represents a member selected from the group consisting of a bivalent aliphatic hydrocarbon group having 1 to 5 carbon atoms, a bivalent aliphatic hydrocarbon group having 1 to 5 carbon atoms which is substituted by a carboxylic acid group or a salt thereof, a bivalent aromatic radical which maybe substituted by the aforementioned substituents R and R especially bivalent aromatic hydrocarbon radicals of the benzene series and bivalent aromatic hydrocarbon radicals of the benzene series which are substituted by a hydroxy group;

Y represents an oxygen atom;

Z represents a member selected from the group consisting of a carboxylic acid group, a sulfonic acid group and a salt of said groups, especially an alkali metal salt and an ammonium salt;

n represents 0 or 1.

The compounds are added sions in quantities from 0.1 g. to 15 g. per mole of silver halide. They are preferably added, as aqueous solutions, to the photographic emulsions ready for casting or coating. Moreover, they may be added to other layers of the light-sensitive materials such as to a protective layer, a filter layer, an intermediate layer, an antihalation layer or a baryta coating. The support of the photographic material may be a film support, a paper support or any other support of sheetlike structure.

Hereinafter follow specific examples of suitable compounds.

to the photographic emul- (XVIII) on on -CH2NH- l sour (XIX) on CH=NC Hr-C 0 0 K (xx) 0H Other specifically suitable compounds are the free acids that correspond to the potassium salt compound I, the potassium salt compound III, the potassium salt compound X, and the dipotassium salt compound XVI.

Most of these compounds are described in the literature, for example, by M. Bergmann, H. Ensslin, L. Zervas in Berichte der Deutschen Chemischen Gesellschaft, 58 (1925), pages lO3443 and by G. L. Eichhorn, N. D. Marchand in J. Am. Chem. Soc., 78 (1956), pages 2688- 91. The azomethin compounds can be prepared by reacting in aqueous solution one mole of optionally substituted, aldehyde with one mole of an alkali metal salt of an amino acid. The hydrogenation of the azomethine bond can easily be effected in aqueous solution, using a Raney-nickel catalyst.

The compounds represented by the above formulae may be produced as follows:

COMPOUND I 70 grams of the halfester of ethanolamine and sulfuric acid are mixed with 35 grams of potassium carbonate and 350 milliliters of water. The mixture has added thereto drop by drop 61 grams of salicyl aldehyde. After 1 hour of stirring the potassium salt which has formed is precipitated by adding 400 milliliters of methanol to the reaction mixture. The product crystallizes in needles, which are sucked off and washed with a little methanol. Yield: grams.

COMPOUND II 70 grams of the halfester of ethanolamine and sulfuric acid are mixed with 35 grams of potassium carbonate and 350 milliliters of water. The mixture has added thereto at room temperature drop by drop a solution of 96 grams of 3,5-dichl0r0-2-hydr0xybenza1dehyde and 230 milliliters of tetrahydrofuran. Thereafter the reaction mixture is stirred for 2 to 3 hours and has added thereto 450 milliliters of isopropanol. The precipitate which has formed is sucked off and washed with a little propanol. Yield: grams of a yellow product. M.P.: 204 C.

COMPOUND III A mixture of 70 grams of a halfester of ethanolarnine and sulfuric acid, 35 grams of potassium carbonate and 300 milliliters of water has added thereto while stirring and while cooling with iced water drop by drop a solution of 2-hyd-r0xy-3-methoxybenzaldehyde in 100 milliliters of tetrahydrofuran. Thereafter the reaction mixture is stirred for 2 hours and then the compound which has formed is precipitated by adding 800 milliliters of isopropanol to the reaction mixture. The precipitate is sucked ofi and Washed with a little ether. Yield: 100 grams of a yellow colored product. M.P.: C.

COMPOUND \IV The compound is produced according to the prescription given for the preparation of compound IV with the variation that the compound I is used instead of compound III. M.P.: 140-142 C.

COMPOUND VI 400 grams of a 15-20% aqueous solution of the sodium salt of taurin has added thereto drop by drop 61 grams of salicyl aldehyde. After a short time the compound crystallizes out in the form of small plates which are isolated by suction filtration. Yield: 85 grams.

COMPOUND VII The compound is prepared according to the prescription given for compound VI with the variation that a solution of potassium salt of methyltaurin is used instead of the sodium salt of taurin.

COMPOUND VIII A solution of 42 grams of 4-aminobenzoic acid, 21 grams of potassium carbonate, 300 milliliters of water has added thereto drop by drop 37 grams salicyl aldehyde. The compound which has formed precipitates in the yield of 75 grams. It may be recrystallized from methanol diluted with water.

COMPOUND IX 40 grams of the compound VIII are dissolved in 350 milliliters of water, then hydrogenated at 70 C. and under a hydrogen pressure of 50 atmospheres by means of a Raney-nickel catalyst. The catalyst is removed by filtration and the reaction mixture is acidified by means of concentrated hydrochloric acid and concentrated under vacuum. There are formed crystals in the form of small plates which are crystallized from. water.

COMPOUND X The compound. is produced according to the method disclosed by M. Bergmann et al. in Berichte der Deutschen Chemischen Gesellschaft 58 (1925) pages 103443.

COMPOUND XI Thecompound is prepared according to the method disclosed by J. Korbe and V. Svoboda in Chemical Abstracts, 55 (1961), column 4437c.

COMPOUND XII A solution of 37 grams of glycocoll and 35 grams of potassium carbonate in 100 milliliters of water has added thereto drop by drop a solution of 3,5-dichloro-2-hydroxy benzaldehyde in 230 milliliters of tetrahydr-ofuran. The reaction product precipitates quickly, especially after 300 milliliters of isopropanol have been added to the reaction mixture. The product may be recrystallized from methanol. Yield: 135 grams. M.P.: 264 C.

COMPOUND XIII 40 grams of the compound XII are dissolved in 300 milliliters of water and hydrogenated at 50 C. and under a hydrogen pressure of 50 atmospheres by means of a Raney-nickel catalyst. The catalyst is removed by filtration. Thereafter, the reaction mixture is adjusted to a pH value of 4 by means of concentrated hydrochloric acid. 1 After cooling the product precipitates. Yield: 30 grams. M.P.: 212213 C.

COMPOUND XIV A mixture of 4-aminobutyric acid, 27 grams of potassium carbonate and 50 milliliters of Water has added thereto 48 grams of salicyl aldehyde drop by drop while stirring. Thereafter the solution is concentrated under vacuum and the compound formed is precipitated by isopropanol. Yield: 60 grams. M.P.: C.

COMPOUND XV 15 grams of compound XIV are dissolved in milliters of water and hydrogenated at 50 C. and under hydrogen pressure of 50 atmospheres by means of a Raney-nickel catalyst. The catalyst is then removed by filtration and the reaction mixture is adjusted to a pH value of 6 by means of hydrochloric acid thereby precipitating the compound which has formed. Yield: 10 grams. M.P.: l75176 C.

COMPOUND XVI The compound is prepared according to the method described by M. Bergmann et al. in Berichte der Deutschen Chemischen Gesellschaft 58 (1925) pages 1034-43.

COMPOUND XVII The compound is produced according to Us. Patent 2,985,646.

COMPOUND XVIII 30 grams of compound XVII are dissolved in 300 milliliters of water and hydrogenated according to the prescription for compound XV.

COMPOUND XIX 13.8 grams of 2,5-dihydroxy benzaldehyde are dissolved in 20 milliliters of tetrahydrofuran and are added drop by drop while stirring to a solution of 7.5 grams of aminoacetic acid and 7 grams of potassium carbonate in 20 milliliters of water. The potassium salt of the compound which has formed is precipitated by means of isopropanol.

COMPOUND XX 13.8 grams of 2,5-dihydroxybenzaldehyde in 20 milliliters of tetrahydrofuran are added drop by drop while stirring to a solution of 10.3 grams of aminobutyric acid and 7 grams of potassium carbonate in 20 milliliters of water. The potassium salt of the compound which has formed is precipitated by means of isopropanol.

The action of the compounds according to the invention is shown by the following examples:

Example 1 A gelatine layer, containing extremely fine rust particles is applied to a film support. After it is dried, a coating of a fine-grain photographic emulsion is applied at a pH of 6.5 to 7.0; the emulsion contains 57 g. of AgBr per kg. of emulsion (Specimen A). A specimen B differs only from specimen A in that 200 m1. of a 2% aqueous solution of the compound I are added to 1 kg. of the silver bromide emulsion before it is applied to the film support containing rust. After exposure to light and photographic development, the specimen A contains numerous black spots Which are enclosed by halos. Specimen B is free from these defects.

Example 2 200 cc. of a 2% aqueous solution of the compound X are added to 1 kg. of a highly sensitive silver bromiodide emulsion, which is applied, at a pH of 6.0, to a gelatine layer, which has been mixed with an extremely fine iron powder (ferrum reductum) and applied to a support (specimen A). If the silver bromiodide emulsion is applied without adding the compound X to the iron-containing gelatine layer, a comparison material (specimen B) is obtained. After exposing both specimens to light and subsequently photographically developing them, the specimen B shows numerous black specks, while specimen A is satisfactory.

Example 3 A support, on to which is cast a gelatine layer mixed with ferrurn reductum, is provided at pH 6.0, with a layer of a silver chlorobromide emulsion (specimen A). A comparison specimen B is produced using a light-sensitive emulsion to which 200 cc. per kg. of a 2% aqueous solution of the compound X has been added. After exposing both specimens to light and subjecting them to photographic development, the specimen A shows numerous black specks, while specimen B is free from these defects.

We claim:

1. A photographic material comprising in superimposed relationship a support and a light-sensitive silver halide emulsion layer, said material containing a phenolic compound substituted in ortho-position to a phenolic hydroxyl group by a member selected from the group consisting of an azomethinyl group and an aminomethyl group, the nitrogen atoms of which groups are substituted by an organic radical carrying a member selected from the group consisting of a carboxylic acid group, a sulfonic acid group and a salt of said carboxylic acid and sulfonic acid groups.

2. A photographic material comprising in superimposed relationship a support and at least one hydrophilic colloid layer, one such layer being a light-sensitive silver halide emulsion layer, at least one of said layers containing a compound having a formula selected from the group consisting of:

wherein R and R each represents a member selected from the group consisting of a hydrogen atom, a halogen atom, an alkyl group having 1 to 5 carbon atoms, an alkoxy group having 1 to 5 carbon atoms in the alkyl group having 1 to 5 carbon atoms in the alkyl group and a hydroxy group;

X represents a member selected from the group consisting of a bivalent aliphatic hydrocarbon group having 1 to 5 carbon atoms, a bivalent aliphatic hydrocarbon group having 1 to 5 carbon atoms, which is substituted by a carboxylic acid group or a salt thereof, a bivalent aromatic radical which may be substituted by the aforementioned substituents R and R especially bivalent aromatic hydrocarbon radicals of the benzene series which are substituted by a hydroxy group;

Y represents an oxygen atom;

4. A photographic material according to claim 2, wherein said compound is a compound corresponding to the formula:

5. A photographic material according to claim 2, wherein said compound is a compound corresponding to the formula:

l CH=N-O 111-0 0 on 6. A photographic material according to claim 2, wherein said compound is a compound corresponding to the 7. A photographic material according to claim 2, wherein said compound is a compound corresponding to the formula:

on @-om-Nn-tonmo 0 on 8. A photographic material according to claim 2, wherein said compound is a compound corresponding to the formula:

CH=NO H-(CHah-O 0 OH door-r No references cited.

NORMAN G. TORCHIN, Primary Examiner.

C. E. DAVIS, Assistant Examiner, 

2. A PHOTOGRAPHIC MATERIAL COMPRISING IN SUPERIMPOSED RELATIONSHIP A SUPPORT AND AT LEAST ONE HYDROPHILIC COLLOID LAYER, ONE SUCH LAYER BEING A LIGHT-SENSITIVE SILVER HALIDE EMULSION LAYER, AT LEAST ONE OF SAID LAYERS CONTAINING A COMPOUND HAVING THE FORMULA SELECTED FROM THE GROUP CONSISTING OF 